From mboxrd@z Thu Jan 1 00:00:00 1970 From: Prarit Bhargava Subject: Re: [PATCH v8] kernel, add panic_on_warn Date: Sat, 08 Nov 2014 08:29:21 -0500 Message-ID: <545E1AB1.9030001@redhat.com> References: <1415187736-16242-1-git-send-email-prarit@redhat.com> <545B733C.6080903@redhat.com> <20141106220731.GA13590@redhat.com> <545CA765.8010403@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+glkk-kexec=m.gmane.org-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org To: David Rientjes Cc: Andi Kleen , Jonathan Corbet , jbaron-JqFfY2XvxFXQT0dZR+AlfA@public.gmane.org, kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Rusty Russell , linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Fabian Frederick , isimatu.yasuaki-+CUm20s59erQFUHtdCDX3A@public.gmane.org, "H. Peter Anvin" , Masami Hiramatsu , Andrew Morton , linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Vivek Goyal List-Id: linux-api@vger.kernel.org On 11/07/2014 04:09 PM, David Rientjes wrote: > On Fri, 7 Nov 2014, Prarit Bhargava wrote: > >> There very much is. Consider a thread that hits a WARN() and then panics. Then >> somewhere in the panic code the thread hits another WARN() ... and then panics >> again. Previously this would have caused the system to "finish" panick'ing. >> Now it makes the system hang. >> > > Then we're back to square one which is what is obviously the intent of > your patch and the comment that goes along with it: My original reply pointed out that the comment was wrong. we want to clear > panic_on_warn once and not allow multiple panic(). On _this_ thread. The multiple panic across threads cannot occur. So why not just add > the necessary synchronization to make sure that happens when WARN() > happens on two cpus simultaneously? See above. P. >